The principal object of this research is to determine the in vivo and in vitro meiotic complements of human ova at first and second metaphase stages in normal and abnormal states. Attention will be paid to scoring and classifying chiasmata frequencies, recording non- disjunctional events and analyzing the spontaneous frequency of structural heterozygosity and aneuploidy. Specific carriers of structural heterozygosities will be studied with superovulation techniques for behavior of their involved chromosomes in meiosis for counselling purposes. Models for studying the intracellular environment of meiotic chromosomes will be sought by analyses of polar and mid-body formation, localization of tagged human pituitary follicle-stimulating and luteinizing hormone, mitochondrial migration, and ovarian X chromosome loss. Comparisons with other female primates' meiotic behavior will also be made as part of a search for unique factors which may induce abnormal meiotic behavior in the human female germ cells.